Discharge device



Dec. 23, 1941.

H. J. SPANNER ETAL DISCHARGE DEVICE Original Filed 061:. 4, 1929 Hans J. Spanner I OsKar Gadamef eh" Att ey for; and

Patented 1:... 23, 1941 DISCHARGE DEYICE Hans J. Spanner and Oskar Gadamer, Berlin,

Germany, asslgnors, by direct and mesne assignments, to General Electric Company,

poration of New York Original application October 4, 1929, Serial No. 397,427. Divided and this application October a cor- 22, 1936, Serial No. 106,958. In Germany July 3 Claims. (Cl. 176-122) This invention relates to gaseous electrical discharge devices and more particularly to such devices in which an electrode is heated to glowing temperature by the action of the discharge.

This application is a division of. application Ser. No. 397,427,-flled Oct. 4, 1929, and now U. S. Patent No. 2,073,885 issued March 16, 1937. As. described in prior applications of the applicant, Spanner, alone and with others, especially Serial No. 351,368, filed March 30, 1929 and Serial No. 387,986, filed August 23, 1929 there have been developed cathodes for electric discharge tubes which are capable of sustaining discharges at 220 volts either direct current or alternating-current,

vices have been employed which require a plu-' rality of leading-in wires in each stem, many of the devices requiring three or more wires in each stem. Y

One object of our present invention is to provide an improved and simplified construction wherein only one'lead-in wire is required. The foregoing and other objects of the invention may best be understood from the following description of one embodiment thereof taken in connection with the accompanying drawing in which' Fig. 1- is a plane view of a discharge tube showing the cathodes and supporting structure;

Fig. '2 is an'enlarged perspective view of one of the cathodes and the supporting structure there- I Fig. 3 is a greatlyenlarged perspective view showing the construction in detail of one turn of the cathode helix. 7

Referring to the drawing more in detail the reference character ll indicates a gas discharge device with enlarged end portions l2 and I2 in each of which there is sealed the usual stem ll. A single leading-in wire I! is sealed into each stem and carries a supporting frame It. A closed loop I! is secured to the supporting frame as at I! and. I9 and is supported thereby in such a manner that it lies disposed substantially peralternately as a cathode and as an anode as the polarity of the potential difference across the tube terminals is periodically reversed. Small pieces of magnesium 2| may be mounted on the loop l1 and secured thereto in any suitable manner as by bending over and clinching. If desired provision may also be made for additional quancurrents in the closed loop II. A coil-23 having its axis in the same general direction as axis of the loop I! is positioned around the tube ll and is supplied with high frequency current byany suitable means not shown. The coil 23 is shown 'at one end only but it is to be understood that a similar coil may be provided at the other end.

In order to facilitate the starting of the discharge the outer wall of the glass tube may be provided with-a conductive coating. This may be in the form of a bronze varnish, one portion of such coating being shown at 24 which portion is connected with one of the leading-in wires IS. The other portion is indicated at 25 and is connected with the other leading-in wire IS. A space as indicated at 28 separates the two portions of the conductive coating and is preferably .positioned near one of the cathodes. It is to be understood that the thicknessof these coatings asishown onthe drawing is greatly exagger- 7 two portions 2'! and 28 of the coating being separated by a space 29 near the opposite cathode 20. It is not essential that there shall be two coatings, one on each side of the tube, but such an arrangement is advantageous in case one of the conductive coatings fails to function to start the discharge. For red tubes 9. gold varnish is preferable and for blue tubes a silver varnish.

The cathode may have associated therewith ,special activating materialssuch as barium or compounds thereof and preferably with the addition ofamphoterlc compounds and may be constructed in the form of a thom-crown-cathode.

, Such a construction is shown in Fig. 3. A plurality of wires "are loosely twisted together and atcertain' points may be cut and pulled outwardly as indicated at 8| giving to the whole arrangement the appearance of a crown of thorns. The discharge takes place quite readily at the points and thereafter passes over to the other portions of the cathode. The interstices in the loosely arranged wires afford space for activating material such as barium and by the construction shown such material is well held in place-mechanically.

pressure of. about 2 millimeters when the tube may be sealed ofi and the ultimate formation ot the cathode undertaken together with the cleaning of the rare gases in thesealed-ofi condition. For this purpose the two leading-in wires l5 are connected through a ballast resistance to a 220-volt alternating current circuit. When the discharge current reaches a value of three to ten amperes the cathodes and the loops start to glow and the magnesium gets so hot that it vaporizes and through its getter effect purifies the rare gases. The tube may also be filled with inert gas ,with the addition of metallic vapor. Indischarge tubes designed for operation on r alternating current circuits the cathodes at each end of the tube are of the same construction. When the tube is designed for operation on direct current circuits only, one end may be constructed as an anode'of any suitable type and material such as carbon or sheet nickel and the anode may be provided if desired with getter material. The above described discharge tube may be used for various'purposes, especially for neon tubes operating directly from the supply lines,

embodiment of the invention'is for the purpose of illustration only and various changes may be and scope of the invention as defined in the subjoined claims.

We claim: p

1. In a discharge tube adapted to start with cold cathode filled with inert gas and an addition of metallic vapor, a cathode having activated material to increase its emissivity, a loop forming in conjunction with said cathode a closed circuit, a supporting frame for said loop the loop being disposed perpendicularly to the frame, and a leading-in wire for supporting said frame.

2.,In a discharge tube adapted to start with cold cathode filled with inert gas with an addition of metallic vapor, a cathode having activated material to increase its emissivity, a loop forming in conjunction with said cathode a made therein without departing from the spirit closed circuit, a supporting frame for said loop,

the loop being disposed perpendicularly to the frame, a leading-in wire for supporting said frame, and pieces of magnesium secured to said loop and frame.

3. In a discharge tube adapted to start' with cold cathode filled with inert gas with an addition of metallic vapor, a cathode having activated material to increase its emissivity, a loop forming in conjunction with said cathode a closed circuit, a supporting frame for said loop the loop being disposed perpendicularly to the frame, a leading-in wire for supporting said frame, and a receptacle for getter material positioned on said frame and open toward the glass of the tube.

HANS J. SPANNER. OSKAR GADAMER. 

